Google (NASDAQ: GOOG) shares fell more than 7 percent on Friday after its quarterly results came in short of expectations, leading some analysts to cut price targets on concerns about growth.

Some investors also disliked Google's decision that CEO Eric Schmidt would no longer participate in earnings conference calls, even though a number of prominent CEOs, including Apple's, IBM's and Microsoft's, are often absent from such calls.

"A significant revenue driver beyond core search has not materialized and it's becoming tougher for the company to beat numbers," Anmuth wrote in a research note.

Reducing his forecast to $650 from $675, Anmuth added that sequential revenue growth and margins were lighter than expected. But he kept his "overweight" rating.

Other analysts were less downbeat. In-Stat analyst Jim McGregor said Google could continue to lean heavily on its core search business because it still holds potential for growth.

"The advertising model for TV, print and stuff like that is tanking," he said. "I don't think there is any limit to the growth in terms of online advertising because everything is going online."

Still, in the longer-term, concerns were increasing over whether Google can keep growing at a red-hot pace amid mounting regulatory and legal challenges and a partial withdrawal from China in a row over censorship.

The world's No. 1 search engine is facing an increasing threat from Apple (NASDAQ: AAPL) in the nascent mobile advertising business and questions about whether it can diversify successfully away from search, despite a series of initiatives.

Margin pressure

On Thursday, Google posted a 23 percent increase in revenue as Internet advertising rebounded. But investors had grown accustomed to seeing blowout results, and investors took profit.

At least four brokerages, including BofA Merrill Lynch, raised their price targets on Google on Friday.

"Google should begin to generate significant revenues from alternative sources beyond search this year, with display advertising and YouTube monetization the biggest near-term opportunities," Post said. He raised his price target on Google to $685 from $670 and maintained a "buy" rating.

But other analysts highlighted short-term concerns over rising costs at Google, which said it would begin hiring aggressively and investing to sustain its pace of growth.

Kaufman Bros analyst Aaron Kessler said he expected costs to be more front-end-loaded this year, and that overall expense growth would moderate. Still, he cut his price target on the stock to $725 from $740, and lowered his 2010 and 2011 profit estimates. He maintained a "buy" rating on the stock.

Analysts also highlighted concerns about Thursday's announcement that Schmidt will no longer address investors on quarterly earnings conference calls. In a research note, Stifel Nicolaus's George Askew called Schmidt's absence "troubling."

"The investors think it's significant, it generates another layer of speculation, puts another log on the fire for the bear case," said BGC Financial analyst Colin Gillis. "People are concerned there's something wrong."

Chief Financial Officer Patrick Pichette, denying any internal rift, urged investors not to read beyond the fact the company was trying to "streamline" the process.